Compatibilized polypropylene heterophasic copolymer and polylactic acid blends for injection molding applications

ABSTRACT

Injection molded articles and process of forming the same are described herein. The processes generally include providing a polyolefin including one or more propylene heterophasic copolymers, the polyolefin having an ethylene content of at least 10 wt. % based on the total weight of the polyolefin; contacting the polyolefin with a polylactic acid and a reactive modifier to form a compatiblized polymeric blend, wherein the reactive modifier is produced by contacting a polypropylene, a multifunctional acrylate comonomer, and an initiator under conditions suitable for the formation of a glycidyl methacrylate grafted polypropylene (PP-g-GMA) having a grafting yield in a range from 1 wt. % to 15 wt. %; and injection molding the compatibilized polymeric blend into an article.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. patent applicationSer. No. 12/165,051, filed Jun. 30, 2008, entitled “CompatibilizedPolypropylene and Polylactic Acid Blends and Methods of Making and UsingSame,” which is hereby incorporated by reference herein.

FIELD

Embodiments of the present invention generally relate to polymericblends adapted for use in injection molding. In particular, embodimentsof the invention relate to polypropylene impact copolymer and polylacticacid blends adapted for use in injection molding.

BACKGROUND

Synthetic polymeric materials, such as polypropylene and polypropylenecomprising a rubber component (e.g., thermoplastic elastomer), arewidely used in injection molding manufacturing of a variety ofcommercial end-uses including articles for automobiles or automobileparts, such as an interior material structure or article. While articlesconstructed from synthetic polymeric materials have widespread utility,these materials tend to degrade slowly, if at all, in a naturalenvironment. In response to environmental concerns, interest in theproduction and utility of more readily biodegradable polymeric materialscomprising polylactic acid, a biodegradable polymer, has beenincreasing. These materials, also known as “green materials”, mayundergo accelerated degradation in a natural environment.

However, the utility of these “green materials” is often limited bytheir poor mechanical and/or physical properties. In particular,polylactic acid is known to be brittle and exhibit low toughness, whichresults in unsatisfactorily low impact strength articles. Blends ofpolylactic acid with elastomeric materials or other impact modifyingpolymers have been proposed, however due to poor proccessability and/orundesirable mechanical properties. Previous blends have not been usedsuccessfully in automotive part applications requiring impact strengthand production efficiency. Therefore, a need exists for a biodegradableblend suitable for injection molding production of articles havingimproved impact strength, thus providing an environmentally friendlyalternative to synthetic polymeric materials or metal in the fabricationof articles such as automotive parts, for example.

SUMMARY

Embodiments of the present invention include an injection molded articleformed by a process including providing a polyolefin including one ormore propylene heterophasic copolymers. The polyolefin having anethylene content of at least 10 wt. % based on the total weight of thepolyolefin: contacting the polyolefin with a polylactic acid and areactive modifier to form a compatiblized polymeric blend, wherein thereactive modifier is produced by contacting a polypropylene, amultifunctional acrylate comonomer, and an initiator under conditionssuitable for the formation of a glycidyl methacrylate graftedpolypropylene (PP-g-GMA) having a grafting yield in a range from 1 wt. %to 15 wt. %; and injection molding the compatibilized polymeric blendinto an article.

One or more embodiments include the article of the preceding paragraph,wherein the one or more propylene heterophasic copolymers has an averageethylene content in a range from 11.5 wt. % to 18 wt. % based on thetotal weight of the copolymers.

One or more embodiments include the article of any preceding paragraph,wherein the polyolefin further includes an elastomer comprisingethylene.

One or more embodiments include the article of any preceding paragraph,wherein the polyolefin further comprises polyethylene.

One or more embodiments include the article of any preceding paragraph,wherein the polyolefin has an ethylene content in a range from 11.5 wt.% to 18 wt. % based on the total weight of the polyolefin.

One or more embodiments include the article of any preceding paragraph,wherein the grafting yield of glycidyl methacrylate (GMA) is at least1.5 wt. %.

One or more embodiments include the article of any preceding paragraph,wherein the grafting yield of glycidyl methacrylate (GMA) is in a rangefrom about 2 wt. % to about 15 wt. %.

One or more embodiments include the article of any preceding paragraph,wherein the article exhibits a flexural modulus in a range from 150 kpsito 500 kpsi.

One or more embodiments include the article of any preceding paragraph,wherein the article exhibits a tensile modulus in a range from 170 kpsito 400 kpsi.

One or more embodiments include the article of any preceding paragraph,wherein the article exhibits a tensile yield strength in a range from2800 psi to 4500 psi.

One or more embodiments include the article of any preceding paragraph,wherein the article exhibits a notched Izod impact strength in a rangefrom 2.1 ft-lb/in to 15 ft-lb/in.

One or more embodiments include the article of any preceding paragraph,wherein the article exhibits a flexural modulus of at least 150 kpsi anda notched Izod impact strength in a range from 2.1 ft-lb/in to 15ft-lb/in.

One or more embodiments include the article of any preceding paragraph,wherein the article exhibits a flexural modulus of at least 150 kpsi anda notched Izod impact strength in a range from 3 ft-lb/in to 15ft-lb/in.

One or more embodiments include the article of any preceding paragraph,wherein the article is an automotive part.

One or more embodiments include methods of forming the injection moldedarticle. The methods generally include providing a polyolefin includingone or more propylene heterophasic copolymers, the polyolefin having anethylene content of at least 10 wt. % based on the total weight of thepolyolefin; melt blending the polyolefin with a polylactic acid and areactive modifier to form a compatiblized polymeric blend, wherein thereactive modifier is produced by contacting a polypropylene, amultifunctional acrylate comonomer, and an initiator under conditionssuitable for the formation of a glycidyl methacrylate graftedpolypropylene (PP-g-GMA) having a grafting yield in a range from 1 wt. %to 15 wt. %; and injection molding the compatibilized polymeric blendinto an article.

One or more embodiments include the method of the preceding paragraph,wherein the one or more propylene heterophasic copolymers has an averageethylene content in a range from 11.5 wt. % to 18 wt. % based on thetotal weight of the copolymers.

One or more embodiments include the method of any preceding paragraph,wherein the melt blending step includes melt blending the polyolefinwith the polylactic acid, an inorganic filler, and the reactive modifierto form the compatiblized polymeric blend.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 illustrates the notched Izod impact strength versus flexuralmodulus for various polymer samples.

FIG. 2 shows the tensile modulus of various polymer samples tested atdifferent temperatures.

FIG. 3 shows the tensile yield strengths of various polymer samplestested at different temperatures.

FIG. 4 shows the room temperature tensile modulus of various polymersamples after being aged at 100° C. for different days.

FIG. 5 shows the room temperature tensile yield strengths of variouspolymer samples after being aged at 100° C. for different days.

FIG. 6 shows a picture of various injection molded polymer specimensafter being aged at 150° C. for about 30 days.

DETAILED DESCRIPTION

Introduction and Definitions

A detailed description will now be provided. Each of the appended claimsdefines a separate invention, which for infringement purposes isrecognized as including equivalents to the various elements orlimitations specified in the claims. Depending on the context, allreferences below to the “invention” may in some cases refer to certainspecific embodiments only. In other cases it will be recognized thatreferences to the “invention” will refer to subject matter recited inone or more, but not necessarily all of the claims. Each of theinventions will now be described in greater detail below, includingspecific embodiments, versions and examples, but the inventions are notlimited to these embodiments, versions or examples, which are includedto enable a person having ordinary skill in the art to make and use theinventions when the information in this patent is combined withavailable information and technology.

Various terms as used herein are shown below. To the extent a term usedin a claim is not defined below, it should be given the broadestdefinition persons in the pertinent art have given that term asreflected in printed publications and issued patents at the time offiling. Further, unless otherwise specified, all compounds describedherein may be substituted or unsubstituted and the listing of compoundsincludes derivatives thereof.

Further, various ranges and/or numerical limitations may be expresslystated below. It should be recognized that unless stated otherwise, itis intended that endpoints are to he interchangeable. Further, anyranges include iterative ranges of like magnitude falling within theexpressly stated ranges or limitations.

Unless otherwise designated herein, all testing methods are the currentmethods at the time of filing.

Compatibilized polymeric compositions including biodegradable polymericcomponents and methods of making and using the same are describedherein. Embodiments of the present invention provide compatibilizedpolymeric blends formed by a process comprising providing a polyolefincomprising one or more polypropylene heterophasic copolymers, whereinthe polyolefin has an ethylene content of at least 10 wt. %, andcontacting the polyolefin with a polylactic acid and a reactive modifierto form a compatibilized polymeric blend. In one or more embodiments,the reactive modifier is produced by contacting a polypropylene, amultifunctional acrylate comonomer, and an initiator under conditionssuitable for the formation of epoxy-functionalized polyolefin having agrafting yield of at least 1 wt. %. The compatibilized polymericcompositions may be used in injection molding manufacturing to form awide variety of injected-molded articles including automotive structuresor parts, such as an interior material structure or article for anautomobile's interior.

Catalyst Systems

The polyolefins may be formed using any suitable catalyst system usefulfor polymerizing olefin monomers. For example, the catalyst system mayinclude chromium based catalyst systems, single site transition metalcatalyst systems including metallocene catalyst systems, Ziegler-Nattacatalyst systems or combinations thereof, for example. The catalysts maybe activated for subsequent polymerization and may or may not beassociated with a support material, for example. A brief discussion ofsuch catalyst systems is included below, but is in no way intended tolimit the scope of the invention to such catalysts.

For example, Ziegler-Natta catalyst systems are generally formed fromthe combination of a metal component (e.g., a catalyst) with one or moreadditional components, such as a catalyst support, a cocatalyst and/orone or more electron donors, for example.

Metallocene catalysts may be characterized generally as coordinationcompounds incorporating one or more cyclopentadienyl (Cp) groups (whichmay be substituted or unsubstituted, each substitution being the same ordifferent) coordinated with a transition metal through π bonding. Thesubstituent groups on Cp may be linear, branched or cyclic hydrocarbylradicals, for example. The cyclic hydrocarbyl radicals may further formother contiguous ring structures, including indenyl, azulenyl andfluorenyl groups, for example. These contiguous ring structures may alsohe substituted or unsubstituted by hydrocarbyl radicals, such as C₁ toC₂₀ hydrocarbyl radicals, for example.

Polymerization Processes

As indicated elsewhere herein, the catalyst systems are used to formolefin-based polymer compositions which are interchangeably referred toherein as polyolefins. Once the catalyst system is prepared, asdescribed above and/or as known to one skilled in the art, a variety ofprocesses may be carried out using the catalyst system to formolefin-based polymers. The equipment, process conditions, reactants,additives and other materials used in polymerization processes will varyin a given process, depending on the desired composition and propertiesof the polymer being formed. Such processes may include solution phase,gas phase, slurry phase, bulk phase, high pressure processes orcombinations thereof, for example. (See, U.S. Pat. Nos. 5,525,678;6,420,580; 6,380,328; 6,359,072; 6,346,586; 6,340,730; 6,339,134;6,300,436; 6,274,684; 6,271,323; 6,248,845; 6,245,868; 6,245,705;6,242,545; 6,211,105; 6,207,606; 6,180,735 and 6,147,173, which areincorporated by reference herein.)

In certain embodiments, the processes described above generally includepolymerizing one or more olefin monomers to form olefin-based polymers.The olefin monomers may include C₂ to C₃₀ olefin monomers, or C₂ to C₁₂olefin monomers (e.g., ethylene, propylene, butene, pentene,4-methyl-1-pentene, hexene, octene and decene), for example. It isfurther contemplated that the monomers may include olefinic unsaturatedmonomers, C₄ to C₁₈ diolefins, conjugated or nonconjugated dienes,polyenes, vinyl monomers and cyclic olefins, example. Non-limitingexamples of other monomers may include norbomene, norbornadiene,isobutylene, isoprene, vinylbenzycyclobutane, styrene, alkyl substitutedstyrene, ethylidene norbornene, dicyclopentadiene and cyclopentene, forexample. The formed polymer may include homopolymers, copolymers orterpolymers, for example.

Examples of solution processes are described in U.S. Pat. Nos.4,271,060, 5,001,205, 5,236,998 and 5,589,555, which are incorporated byreference herein.

One example of a gas phase polymerization process includes a continuouscycle system, wherein a cycling gas stream (otherwise known as a recyclestream or fluidizing medium) is heated in a reactor by heat ofpolymerization. The heat may be removed from the cycling gas stream inanother part of the cycle by a cooling system external to the reactor.The cycling gas stream containing one or more monomers may becontinuously cycled through a fluidized bed in the presence of acatalyst under reactive conditions. The cycling gas stream is generallywithdrawn from the fluidized bed and recycled back into the reactor.Simultaneously, polymer product may be withdrawn from the reactor andfresh monomer may be added to replace the polymerized monomer. Thereactor pressure in a gas phase process may vary from about 100 psig toabout 500 psig, or from about 200 psig to about 400 psig or from about250 psig to about 350 psig, for example. The reactor temperature in agas phase process may vary from about 30° C. to about 120° C., or fromabout 60° C. to about 115° C., or from about 70° C. to about 110° C. orfrom about 70° C. to about 95° C., for example. (See, for example, U.S.Pat. Nos. 4,543,399; 4,588,790; 5,028,670; 5,317,036; 5,352,749;5,405,922; 5,436,304; 5,456,471; 5,462,999; 5,616,661; 5,627,242;5,665,818; 5,677,375 and 5,668,228, which are incorporated by referenceherein.)

Slurry phase processes generally include forming a suspension of solid,particulate polymer in a liquid polymerization medium, to which monomersand optionally hydrogen, along with catalyst, are added. The suspension(which may include diluents) may be intermittently or continuouslyremoved from the reactor where the volatile components can be separatedfrom the polymer and recycled, optionally after a distillation, to thereactor. The liquefied diluent employed in the polymerization medium mayinclude a C₃ to C₇ alkane (e.g., hexane or isobutane), for example. Themedium employed is generally liquid under the conditions ofpolymerization and relatively inert. A bulk phase process is similar tothat of a slurry process with the exception that the liquid medium isalso the reactant (e.g., monomer) in a bulk phase process. However, aprocess may be a bulk process, a slurry process or a bulk slurryprocess, for example.

In a specific embodiment, a slurry process or a bulk process may becarried out continuously in one or more loop reactors. The catalyst, asslurry or as a dry free flowing powder, may be injected regularly to thereactor loop, which can itself be filled with circulating slurry ofgrowing polymer particles in a diluent, for example. Optionally,hydrogen (or other chain terminating agents, for example) may be addedto the process, such as for molecular weight control of the resultantpolymer. The loop reactor may be maintained at a pressure of from about27 bar to about 50 bar or from about 35 bar to about 45 bar and atemperature of from about 38° C. to about 121° C., for example. Reactionheat may be removed through the loop wall via any suitable method, suchas via a double-jacketed pipe or heat exchanger, for example.

Alternatively, other types of polymerization processes may be used, suchas stirred reactors in series, parallel or combinations thereof, forexample. Upon removal from the reactor, the olefin-based polymer (i.e.,polyolefin) may be passed to a polymer recovery system for furtherprocessing, such as addition of additives and/or extrusion, for example.

Polymer Product

The compatibilized polymeric compositions are formed by contacting apolyolefin (PO), a polylactic acid (PLA), and a reactive modifier underconditions suitable for the formation of a blended material (i.e.,compatibilized polymeric blend).

The polyolefin may be one or more polyolefins. The polyolefin (andblends thereof) formed via the processes described herein may include,but are not limited to, polyethylene, elastomers, plastomers, highdensity polyethylenes, low density polyethylenes, medium densitypolyethylenes, polypropylene, polypropylene copolymers, copolymersthereof and combinations thereof, for example.

The polyolefin of the present invention comprises a propylene-basedpolymer. As used herein, the term “propylene-based” is usedinterchangeably with the terms “propylene polymer” or “polypropylene”and refers to a polymer having at least about 50 wt. %, or at leastabout 70 wt. %, or at least about 75 wt. %, or at least about 80 wt. %,or at least about 85 wt. % or at least about 90 wt. % polypropylenerelative to the total weight of polymer, for example.

In an embodiment, the propylene-based polymer suitable for use in thisdisclosure may have a density of from about 0.895 g/cc to about 0.920g/cc, or from about 0.900 g/cc to about 0.915 g/cc, or from about 0.905g/cc to about 0.915 g/cc as determined in accordance with ASTM D1505.

In an embodiment, the propylene-based polymer may have a melting point(T_(m)) (as measured by differential scanning calorimetry) of at leastabout 140° C. or from about 150° C. to about 175° C., or from about 155°C. to about 170° C., for example.

In an embodiment, the propylene-based polymer may have a melt flow rate(MFR) (as determined in accordance with ASTM D-1238 condition “L”) of atleast about 1 dg/min., or from about 2 dg/min. to about 50 dg/min., orfrom about 5 dg/min. to about 40 dg/min., for example.

The propylene-based polymer comprises one or more polypropyleneheterophasic copolymers (or impact copolymer). Polypropyleneheterophasic copolymer (PPHC) refers to a polypropylene or polypropylenecopolymer matrix phase joined to (i.e., containing) a copolymer phase orcomponent. The copolymer phase includes ethylene and higher alpha-olefinpolymer such as amorphous ethylene-propylene copolymer, for example.

The copolymer phase of a PPHC may be a random copolymer of propylene(C₃) and ethylene (C₂), also referred to as an ethylene/propylene rubber(EPR). Without wishing to be limited by theory, the EPR portion of thePPHC has rubbery characteristics which, when incorporated within thematrix of the homopolymer component, may function to provide increasedimpact strength to the PPHC. In an embodiment, the EPR portion of thePPHC comprises greater than 18 wt. % of the PPHC, alternatively fromgreater than 18 wt. % to 30 wt. % of the PPHC, alternatively at least 22wt. % of the PPHC.

The amount of ethylene present in the EPR portion of the PPHC may befrom 35 wt. % to 50 wt. %, alternatively from 40 wt. % to 45 wt. % basedon the total weight of the EPR portion. The amount of ethylene presentin the EPR portion of the PPHC may be determined spectrophotometricallyusing a Fourier transform infrared spectroscopy (FTIR) method.Specifically, the FTIR spectrum of a polymeric sample is recorded for aseries of samples having a known EPR ethylene content. The ratio oftransmittance at 720 cm⁻¹/900 cm⁻¹ is calculated for each ethyleneconcentration and a calibration curve may then be constructed. Linearregression analysis on the calibration curve can then be carried out toderive an equation that is then used to determine the EPR ethylenecontent for a sample material.

In an embodiment, the copolymer phase of a PPHC may have an ethyleneconcentration of at least 8 wt. %, or at least 10 wt. %, or at least 11wt. %, or in a range from 11.5 wt. % to 18 wt. %, or in a range from12.5 wt. % to 15 wt. % based on the total weight of the PPHC. Ingeneral, increasing the ethylene content, increases the impact strengthof the PPHC. Examples of suitable polypropylene heterophasic copolymerinclude without limitation products Total 5571 (having a C₂ content of11 wt. %), PPC7810 (having a C₂ content of 13.5 wt. %) and PPC9760(having a C₂ content of 8 wt. %), which are commercially availableproducts from Total Petrochemicals.

When the propylene-based polymer comprises more than one polypropyleneheterophasic copolymer, the ethylene content of the EPR portions formultiple PPHCs may be calculated as an average ethylene content byweight-averaging the ethylene contents of the individual PPHCs based onthe relative quantities of each PPHC. For example, a polyolefincomprising 22 wt. % of a first PPHC which has an ethylene content of 8wt. % (e.g., PPHC 9760), and 65 wt. % of a second PPHC which has anethylene content of 13.5 wt. % (e.g., PPHC 7810), has an averageethylene content value equal to 10.5 wt. %, as calculated by multiplyingthe relative quantities of the individual PPHCs by their ethylenecontent (i.e., 0.22×8 wt. %+0.65×13.5 wt. %=10.5 wt. %).

In an embodiment, the one or more polypropylene heterophasic copolymersmay have a concentration in a range from about 80 wt. % to 100 wt. %based on the total weight of the polyolefin.

In an embodiment, the propylene-based polymer may optionally includepolypropylene homopolymer. Unless otherwise specified, the term“polypropylene homopolymer” refers to propylene homopolymers, i.e.,polypropylene, or those polyolefins composed primarily of propylene andmay contain up to 0.5 wt. % of other comonomers, including but notlimited to C₂ to C₈ alpha-olefins (e.g., ethylene and 1-butene), whereinthe amount of comonomer is insufficient to change the amorphous orcrystalline nature of the propylene polymer significantly. Despite thepotential presence of small amounts of other comonomers, thepolypropylene is generally referred to as a polypropylene homopolymer.

In an embodiment, the propylene-based polymer may optionally includepolypropylene-based random copolymer. Unless otherwise specified, theterm “propylene-based random copolymer” refers to those copolymerscomposed primarily of propylene and an amount of at least one comonomer,wherein the polymer includes at least about 0.1 wt. %, or at least about0.8 wt. %, or at least about 2 wt. %, or from about 0.5 wt. % to about5.0 wt. % comonomer relative to the total weight of polymer, forexample. The comonomers may be selected from C₂ to C₁₀ alkenes. Forexample, the comonomers may be selected from ethylene. propylene,1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene,4-methyl-1-pentene, and combinations thereof. In one specificembodiment, the comonomer includes ethylene. Further, the term “randomcopolymer” refers to a copolymer formed of macromolecules in which theprobability of finding a given monomeric unit at any given site in thechain is independent of the nature of the adjacent units.

In an embodiment, the propylene-based polymer may be formed from ametallocene catalyst. In another embodiment, the propylene-based polymeris formed from a Ziegler-Natta catalyst.

In an embodiment, the polyolefin of the present invention may optionallyinclude an elastomer. The elastomer may provide additional impactresistance to the compatibilized polymeric blend. In effect,incorporation of an elastomer may effectively increase the elastomericimpact behavior of the blend provided by the ethylene/polypropylenerubber portion of the PPHC. Thus, incorporation of an elastomer may beparticularly useful when the PPHC has an ethylene content (or average C₂content) less than about 12.5 wt. %. Examples of suitable elastomersinclude, without limitation, elastomers comprising ethylene such asethylene propylene rubber (EPR) and ethylene propylene diene monomer(EPDM), for example. EPDM is an elastomer that is similar to the EPRportion in the polypropylene heterophasic copolymers. The elastomer mayhave a concentration in a range from about 1 wt. % to 20 wt. % based onthe total weight of the polyolefin.

The polyolefin of the present invention may optionally includepolyethylene. Polyethylenes, such as high density polyethylene (HDPE),for example, may also provide additional impact resistance as well asscratch-resistance to the compatibilized polymeric blend while alsoincreasing the stiffness of the blend. The incorporation of apolyethylene may be particularly useful when the PPHC has an ethylenecontent (or average C₂ content) less than about 12.5 wt. %. An exampleof a suitable HDPE includes, without limitation, product M6091commercially available from Total Petrochemicals. The polyethylene mayhave a concentration in a range from about 1 wt. % to 20 wt. % based onthe total weight of the polyolefin.

In an embodiment, the polyolefin may have a propylene concentration ofat least 30 wt. %, or from about 30 wt. % to about 96 wt. %, or fromabout 40 wt. % to about 96 wt. %, or from about 40 wt. % to about 85 wt.% based on the total weight of the compatibilized polymeric composition,for example.

In an embodiment, the polyolefin may have an ethylene concentration ofat least 10 wt. %, or at least 11 wt. %, or in a range from 11.5 wt. %to 18 wt. %, or in a range from 12.5 wt. % to 15 wt. % based on thetotal weight of the polyolefin.

The one or more polyolefins (PO) are contacted with a polylactic acid(PLA) and a reactive modifier to form a compatibilized polymericcomposition (which may also be referred to herein as a compatibilizedblend or compatibilized blended material). Such contact may occur by avariety of methods. For example, such contact may include blending thepolyolefin and the polylactic acid in the presence of the reactivemodifier under conditions suitable for the formation of a blendedmaterial. Such blending may include dry blending, melt blending, meltcompounding, or combinations thereof, by known blending techniques suchas mixing and extrusion (e.g., twin-screw extrusion), for example.

The polylactic acid may include any polylactic acid capable of blendingwith an olefin based polymer. For example, the polylactic acid may heselected from poly-L-lactide (PLLA), poly-D-lactide (PDLA),poly-LD-lactide (PDLLA) and combinations thereof. The polylactic acidmay he formed by known methods, such as dehydration condensation oflactic acid (see, U.S. Pat. No. 5,310,865, which is incorporated byreference herein) or synthesis of a cyclic lactide from lactic acidfollowed by ring opening polymerization of the cyclic lactide (see, U.S.Pat. No. 2,758,987, which is incorporated by reference herein), forexample. Such processes may utilize catalysts for polylactic acidformation, such as tin compounds (e.g., tin oetylate), titaniumcompounds (e.g., tetraisopropyl titanate), zirconium compounds (e.g.,zirconium isopropoxide), antimony compounds (e.g., antimony trioxide) orcombinations thereof, for example.

In an embodiment, the polylactic acid may have a specific gravity offrom about 1.228 to about 1.255, or from about 1.23 to about 1.25 orfrom about 1.235 to about 1.245 (as determined in accordance with ASTMD792), for example.

In an embodiment, the polylactic acid may exhibit a crystalline melttemperature of from about 140° C. to about 190° C., or from about 145°C. to about 185° C. or from about 150° C. to about 180° C. (asdetermined in accordance with ASTM D3418).

In an embodiment, the polylactic acid may exhibit a glass transitiontemperature of from about 45° C. to about 85° C., or from about 50° C.to about 80° C. or from about 50° C. to about 70° C. (as determined inaccordance with ASTM D3417).

In an embodiment, the polylactic acid may exhibit a tensile yieldstrength of from about 4,000 psi to about 25,000 psi or from about 5,000psi to about 10,000 psi or from about 5,500 psi to about 8,500 psi (asdetermined in accordance with ASTM D638), for example.

In an embodiment, the polylactic acid may exhibit a tensile elongationof from about 0.5% to about 10%, or from about 1.0% to about 8% or fromabout 1.5% to about 6% (as determined in accordance with ASTM D638), forexample.

In an embodiment, the polylactic acid may exhibit a notched Izod impactof from about 0.1 ft-lb/in to about 0.8 ft-lb/in, or from about 0.15ft-lb/in to about 0.6 ft-lb/in or from about 0.2 ft-lb/in to about 0.5ft-lb/in (as determined in accordance with ASTM D256), for example.

In an embodiment, the compatibilized polymeric composition may includefrom about 1 wt. % to about 49 wt. %, or from about 3 wt. % to about 20wt. %, or from about 5 wt. % to about 12 wt. % polylactic acid based onthe total weight of the compatibilized polymeric composition, forexample.

As used herein, the term “reactive modifier” refers to polymericadditives that, when directly added to a molten blend of immisciblepolymers (e.g., the polyolefin and the PLA), may chemically react withone or both of the blend components to increase adhesion and stabilizethe blend. The reactive modifier may he incorporated into the polymericcomposition via a variety of methods such as melt blending, meltcompounding, or combinations thereof, and by known blending techniquessuch as mixing and extrusion (e.g., twin-screw extrusion), for example.

The reactive modifier may include functional polymers capable ofcompatibilizing a blend of polyolefin and polylactic acid (PO/PLAblend). The functional polymer is a graftable polyolefin selected frompolypropylene, polyethylene, homopolymers thereof, copolymers thereof,and combinations thereof.

In an embodiment, the reactive modifier comprises anepoxy-functionalized polyolefin. Examples of epoxy-functionalizedpolyolefins suitable for use in this disclosure include withoutlimitation epoxy-functionalized polypropylene such as glycidylmethacrylate grafted polypropylene (PP-g-GMA), epoxy-functionalizedpolyethylene such as polyethylene co-glycidyl methacrylate (PE-co-GMA),and combinations thereof. An example of an epoxy-functionalizedpolyethylene suitable for use in this disclosure includes LOTADER® GMAproducts such as, for example, product LOTADER® AX8840, which is arandom copolymer of ethylene and glycidyl methacrylate (PE-co-GMA)having 8% GMA content (as measured by FTIR), or product LOTADER® AX8900which is a random terpolymer of ethylene, methyl acrylate and glycidylmethacrylate having 8% GMA content, which are commercially availableproducts from Arkema.

The reactive modifiers may be prepared by any suitable method. Forexample, the reactive modifiers may be formed by a grafting reaction.The reactive modifiers are formed by grafting in the presence of aninitiator, such as peroxide. Examples of initiators may includeLUPERSOL® 101 and TRIGANOX® 301, commercially available from Arkema.Inc. The grafting reaction may occur in a molten state inside of anextruder, for example (e.g., “reactive extrusion”).

In another embodiment, the reactive modifier comprises PP-g-GMA.PP-g-GMA may be prepared by any suitable method such as for example bygrafting CMA onto polypropylene in the presence of an initiator such asperoxide. The grafting reaction of GMA onto PP may be conducted in amolten state inside an extruder such as for example a single screwextruder or a twin-screw extruder. For example, a feedstock comprisingPP, GMA, and initiator (i.e., peroxide) may be fed into an extruderreactor sequentially along the extruder, alternatively the feedstock(i.e., PP, GMA, and initiator) may be pre-mixed outside and fed into theextruder. In an embodiment, the initiator may be used in an amount offrom 0.03 wt. % to 2 wt. %, or from 0.2 wt. % to 0.8 wt. %, or from 0.3wt. % to 0.5 wt, % based on the total weight of the compatibilizedpolymeric blend.

In an alternate embodiment, the reactive modifier PP-g-GMA may beprepared using a multi-functional acrylate comonomer in order to providethe resulting PP-g-GMA reactive modifier with a higher grafting yield,as compared to the grafting yields obtainable (i.e., less than 1 wt. %)by employing conventional grafting methods. Incorporation of themulti-functional acrylate comonomer boosts the grafting reaction toobtain a highly grafted GMA having a grafting yield in a range from 1wt. % to 15 wt. %, or at least 1.5 wt. %, or in a range from about 2 wt.% to about 3 wt. %. The PP-g-GMA prepared using a multi-functionalacylate comonomer is hereinafter referred to as a highly grafted GMA(“HGGMA”).

The HGGMA is prepared by grafting GMA onto polypropylene in the presenceof an initiator and a multi-functional acrylate comonomer. Themulti-functional acrylate comonomers may comprise polyethylene glycoldiacrylate, alkoxylated hexanediol diacrylate, trimethylolpropanetriacrylate (TMPTA), or combinations thereof. Examples ofmulti-functional acrylate comonomers suitable for use in this disclosureinclude without limitation SR256 (polyethylene glycol diacrylate). CD560(alkoxylated hexanediol diacrylate), SR351 (TMPTA), SR9003 (propoxylatedneopentyl glycol diacrylate), SR454 (ethoxylated trimethylolpropanetriacrylate). SR230 (diethylene glycol diacrylate), SR368D (tris(2-hydroxy ethyl)isocyanurate triacrylate), etc. which are commerciallyavailable from Sartomer.

The grafting reaction of GMA onto polypropylene in the presence of aperoxide and the multi-functional acrylate comonomer polyethylene glycoldiacrylate is depicted in Scheme 1.

Without wishing to be limited by theory, the hydrogens on the tertiarycarbon of polypropylene molecules can be easily abstracted in thepresence of peroxide during reactive extrusion, forming polypropylenemacroradicals with unpaired electrons. The polypropylene macroradicalswhich are generally unstable, tend to form free radicals through a stepreferred to as “β-scission.” β-scission refers to a family of reactionswherein bonds that are in a beta-position to a radical are cleavedresulting in the formation of a double bond and a new radical. Theβ-scission reaction is believed to be responsible mainly for theformation of internal double bonds thus its occurrence is correlatedwith the allelic content of the final polymer. β-scission is typicallyfavored over the grafting reaction (i.e., the addition of the GMA)resulting in both a lower grafting of GMA and a polypropylene having alower average molecular weight. However, in the reactions comprising amulti-functional acrylate comonomer, the multi-functional acrylatecomonomer may function to readily capture the polypropylenemicro-radicals resulting in the formation of a more stable intermediate(i.e., polypropylene-acrylate radicals). The relatively stablepropylene-acrylate radicals tend to react more readily with GMA, whichis an acrylate type monomer and consequently favor the graftingreaction.

Furthermore, as shown in Scheme 1, multiple free radicals may exist onthe grafted propylene-acrylate molecules thus making it easier tocapture and initiate the reaction of GMA. The reactivity of GMA towardsacrylate tree radicals may be higher than towards polypropylene tertiarymacro-radicals. Consequently, PP-g-GMA prepared using a reaction mixturecomprising a multi-functional acrylate comonomer may display a higherdegree of grafting than a PP-g-GMA prepared using an otherwise similarcomposition in the absence of a multi-functional acrylate comonomer.PP-g-GMA prepared using a multifunctional acrylate comonomer ishereinafter referred to as a highly grafted GMA (HGGMA).

In an embodiment, the HGGMA reactive modifier is prepared from areaction mixture comprising: a propylene having a concentration in arange from 80 wt. % to 99.5 wt. %, or from 90 wt. % to 99 wt. %, or from95 wt. % to 99 wt. % based on the total weight of the reactive modifier;GMA having a concentration in a range from 0.5 wt. % to 20 wt. %, orfrom 1 wt. % to 10 wt. %, or from 1 wt. % to 5 wt. % grafting componentbased on the total weight of the reactive modifier: a multi-functionalacrylate comonomer having a concentration in a range from 0.5 wt. %, to15 wt. % or from 1.0 wt. % to 10 wt. %, or from 1.0 wt. % to 5.0 wt. %based on the total weight of the reactive modifier: and an initiator(e.g., peroxide) having a concentration in a range from 0.05 wt. % to1.5 wt. %. or from 0.2 wt. % to 0.8 wt. %, or from 0.3 wt. % to 0.5 wt.%.

The amount of grafting of GMA onto the polypropylene may vary dependingon a variety of factors such as the type of materials used andprocessing conditions. Such parameters may be varied by one of ordinaryskill in the art with the benefits of this disclosure to producereactive modifiers having a user-desired grafting yield. In anembodiment, a HGGMA reactive modifier may have a grafting yield ofgreater than 1 wt. %, or from 1 wt. % to 15 wt. %, or greater than 1.5wt. %, or from 1.5 wt. % to 10 wt. %, or from 2 wt. % to 5.0 wt. %, asdetermined by FTIR. This grafting yield is a substantial improvementover conventionally prepared PP-g-GMA which is prepared using anotherwise similar composition but in the absence of a multi-functionalaerylate comonomer. As a result, conventional grafting processes toprepare PP-g-GMA have substantially lower grafting yields. Inparticular, the conventional grafting process normally provides about 3wt. % GMA in the feedstock to produce a PP-g-GMA having a grafting yieldof less than 1% (i.e., in a range from about 0.5% to 0.8%) to produce aPP-g-GMA having less than 1% grafted GMA. In order to increase thequantity of grafted GMA, the conventional grafting process may providethe feedstock with 6 wt. % GMA to produce a PP-g-GMA having less than 2%grafted GMA. However, a disadvantage of this process is that the use ofincreasing amounts of GMA in the feedstock (e.g., 6 wt. %) of a graftingprocess that has a grafting yield of less than 1% is not economical and,thus, not a viable process to provide more highly grafted PP-g-GMA. Incontrast, the incorporation of a multi-functional acrylate comonomerwhich advantageously boosts the grafting of GMA as previously describedherein provides much higher grafting yields and a highly graftedPP-g-GMA. The use of HHGMA as a reactive modifier in the compatibilizedpolymeric compositions imparts better mechanical and thermal propertiesto the compositions, which is understood to be a result of the HHGMAproviding better compatibilzation between the PP/PLA components, ascompared to using conventionally prepared PP-g-GMA (i.e., having a lowerGMA content) as the reactive modifier.

The grafting yield may be determined using any suitable method. Forexample, the grafting yield may be determined by Fourier TransformInfrared Spectroscopy (FTIR) spectroscopy. In an embodiment, a methodfor determining the grafting yield comprises obtaining the FTIR spectraof polymeric samples having a mixture of PP and GMA wherein the amountof each component is known. A calibration curve may be generated byplotting the signal intensity at one or more wavelengths as a functionof component concentration. The FTIR spectra of a PP-g-GMA sample maythen he determined and compared to the calibration curve in order todetermine the grafting yield. This method is described in more detail inAngew Makromol. Chem. 1995, V229 pages 1-13 which is incorporated byreference herein in its entirety.

In an embodiment, the compatibilized polymeric composition is preparedfrom a process comprising contacting the polyolefin and the polylacticacid in the presence of the reactive modifier, wherein the reactivemodifier has a concentration in a range from about 1 wt. % to about 15wt. % or from about 3 wt. % to about 10 wt. % based on the total weightof the compatibilized polymeric composition, for example.

In an embodiment, the compatibilized polymeric composition may alsooptionally comprise one or more additives to impart desired physicalproperties, such as printability, increased gloss, or a reduced blockingtendency of articles formed from a compatibilized polymeric compositiondescribed herein. Examples of additives may include without limitation,stabilizers, ultra-violet screening agents, oxidants, anti-oxidants,anti-static agents, ultraviolet light absorbents, fire retardants,processing oils, mold release agents, coloring agents, pigments/dyes,fillers, and/or other suitable additives. The aforementioned additivesmay be used either singularly or in combination to form variousformulations of the polymer. For example, in the fabrication ofautomotive parts, stabilizers or stabilization agents may be employed tohelp protect the polymer resin from degradation due to exposure toexcessive temperatures and/or ultraviolet light. These additives may beincluded in amounts effective to impart the desired properties.Effective additive amounts and processes for inclusion of theseadditives to the compatibilized polymeric compositions may be determinedby one skilled in the art with the aid of this disclosure.

In an embodiment, the compatibilized polymeric composition may alsooptionally comprise one or more inorganic fillers to increase theflexural modulus and tensile mechanical properties of articles formedfrom a compatibilized polymeric composition described herein.Incorporating one or more inorganic fillers may also increase propertiessuch as the heat distortion temperature and scratch resistance, forexample, of articles formed from a compatibilized polymeric compositiondescribed herein. Suitable inorganic fillers include talc, carbon black,limestone, marble, ceramic, and other common inorganic fillers known toone of skill in the art. For example, the addition of talc to thecompatibilized polymeric composition provides an article formed fromthat composition with improved scratch resistance.

In an embodiment, the compatibilized polymeric composition may includefrom about 1 wt. % to about 60 wt. %, or from about 5 wt. % to about 25wt. %, or from about 10 wt. % to about 20 wt. % inorganic filler basedon the total weight of the compatibilized polymeric composition, forexample.

The compatibilized polymeric composition may be prepared by contactingthe polyolefin, the polylactic acid, and the reactive modifier underconditions suitable for the formation of the compatibilized polymericblend. The polyolefin, the polylactic acid, and the reactive modifiermay be blended via a variety of methods such as melt blending, meltcompounding, or combinations thereof, and by known blending techniquessuch as mixing and extrusion (e.g., twin-screw extrusion), for example.

In an embodiment, the compatibilized polymeric composition may beprepared by contacting a polypropylene heterophasic copolymer, PLA, andan epoxy-functionalized polyolefin (e.g., HGGMA) as the reactivemodifier. In one example, the polypropylene heterophasic copolymer, PLA,and epoxy-functionalized polyolefin components may be dry blended, fedinto an extruder, and melted inside the extruder. The mixing may becarried out using a continuous mixer such as a mixer having anintermeshing co-rotating twin screw extruder for mixing and melting thecomponents of the compatibilized polymeric composition and a singlescrew extruder or a gear pump for pumping the molten mixture (i.e.,compatibilized polymeric composition) out of the continuous mixer. Thecompatibilized polymeric composition may he subsequently dried in anoven or under vacuum.

Without wishing to be limited by theory, formation of a PP-epoxy-PLAgrafted copolymer occurs upon reactive extrusion when at least a portionof the reactive modifier (i.e., epoxy functionalized polyolefin) whichis originally associated with the PP migrates to the PP/PLA interface.The reactive modifier may contact the PLA molecules at the interfacebetween the PP and PLA phases and react with the PLA to formPP-epoxy-PLA grafted copolymers at the interface. The PP-epoxy-PLAcopolymer formed in situ is a compatibilizer that stabilizes the PP/PLAblend by performing multiple functions. In a molten state, thecompatibilizer may decrease the interfacial tension between PP and PLAand improve dispersion of the PLA phase in the PP. Once thecompatibilized polymeric composition solidifies, the compatibilizerremains at the interface of PP and PLA, where it may function tochemically interlink PP and PLA. Thus, the compatibilizers form anadhesive or tie layer that serves to improve the interfacial bondingresulting in compatibilized polymeric compositions having improved phasedispersions and properties when compared to an uncompatibilized PP/PLAblend.

Product Application

The compatibilized polymeric compositions and blends thereof are usefulin applications known to one skilled in the art, such as formingoperations (e.g., film, sheet, pipe and fiber extrusion and co-extrusionas well as blow molding, injection molding and rotary molding). Filmsinclude blown, oriented or cast films formed by extrusion orco-extrusion or by lamination useful as shrink film, cling film, stretchfilm, sealing films, oriented films, snack packaging, heavy duty bags,grocery sacks, baked and frozen food packaging, medical packaging,industrial liners, and membranes, for example, in food-contact andnon-food contact application. Fibers include slit-films, monofilaments,melt spinning, solution spinning and melt blown fiber operations for usein woven or non-woven form to make sacks, bags, rope, twine, carpetbacking, carpet yarns, filters, diaper fabrics, medical garments andgeotextiles, for example. Extruded articles include medical tubing, wireand cable coatings, sheet, thermoformed sheet, geomembranes and pondliners, for example. Molded articles include single and multi-layeredconstructions in the form of bottles, tanks, large hollow articles,rigid food containers and toys, for example.

In an embodiment, the compatibilized polymeric composition is utilizedin injection molding processes to form injection molded articles. Theinjection molded articles may include a wide variety of articlesincluding automotive parts or structures (e.g., automotive dashboard),for example. The injection molded articles may be formed by any suitableinjection molding process known to one of skill in the art. Injectionmolding processes generally include heating the compatibilized polymericcomposition to form a molten polymer and subsequently forcing (i.e.,injecting) the molten polymer into a mold cavity where the moltenpolymer fills the mold cavity thereby taking the desired shape of themold cavity. Thereafter, the molten polymer inside the mold cavity coolsand hardens to form a molded article which is subsequently ejected fromthe mold.

In one example, polypropylene heterophasic copolymer, PLA, and anepoxy-functionalized polyolefin reactive modifier (e.g., HGGMA) may bedry blended, fed into an extruder, and melted inside the extruder. Themixing may be carried out using a mixer having an intermeshingco-rotating twin screw extruder for mixing and melting the componentsinto a compatibilized polymeric blend. The molten compatibilizedpolymeric blend may be fed to a manifold where it is injected throughnozzles into mold cavities. In each mold cavity, the molten blend fillsthe mold cavity, thereby taking on a desired shape of the interior ofthe mold cavity. The molten blend in the desired shape of the articlecools and hardens to form an injection molded article which issubsequently ejected from the mold. In one example, the injection moldedarticle is an automotive part such as an interior automotive part, forexample.

In an embodiment, the compatibilized polymeric composition may exhibit amelt flow rate (MFR) in a range from 0.5 dg/min. to 100 dg/min., or fromto 1 dg/min. to 50 dg/min., or from 5 dg/min. to 40 dg/min.

In an embodiment, the injection molded articles formed from acompatibilized polymeric composition of the type described hereinexhibits a flexural modulus of at least 150 kpsi or in a range from 150kpsi to 500 kpsi, as determined in accordance with ASTM D790. Thestiffness of the injection molded article is reflected in the article'sflexural modulus. The flexural modulus test in broad terms measures theforce required to bend a sample material beam. The force is applied tothe center of the sample beam, while the beam is supported on both ends.

In an embodiment, the injection molded articles formed from acompatibilized polymeric composition of the type described hereinexhibits a tensile modulus of at least 170 kpsi or in a range from 170kpsi to 400 kpsi, as determined in accordance with ASTM D638. Therigidity of the injection molded article is reflected in the article'stensile modulus. The tensile modulus is the ratio of stress to elasticstrain in tension. Therefore, the larger the tensile modulus the morerigid the material, and the more stress required to produce a givenamount of strain.

In an embodiment, the injection molded articles formed from acompatibilized polymeric composition of the type described hereinexhibits a tensile yield strength of at least 2800 psi, or in a rangefrom 2800 psi to 4500 psi, as determined in accordance with ASTM D882.The tensile strength at yield is the force per unit area required toyield a material.

In an embodiment, the injection molded articles formed from acompatibilized polymeric composition of the type described hereinexhibits a notched Izod impact strength of at least 0.7 ft-lb/in, or ina range from 0.7 ft-lb/in to 15 ft-lb/in, or in a range from 2.1ft-lb/in to 15 ft-lb/in, or in a range from 3 ft-lb/in to 15 ft-lb/in,as determined in accordance with ASTM D256. Izod impact is defined asthe kinetic energy needed to initiate a fracture in a polymer samplespecimen and continue the fracture until the specimen is broken. Testsof the Izod impact strength determine the resistance of a polymer sampleto breakage by flexural shock as indicated by the energy expended from apendulum type hammer in breaking a standard specimen in a single blow.The specimen is notched which serves to concentrate the stress andpromote a brittle rather than ductile fracture. Specifically, the Izodimpact test measures the amount of energy lost by the pendulum duringthe breakage of the test specimen. The energy lost by the pendulum isthe sum of the energies required to initiate sample fracture, topropagate the fracture across the specimen, and any other energy lossassociated with the measurement system (e.g., friction in the pendulumbearing, pendulum arm vibration, sample toss energy, etc.).

In an embodiment, the injection molded articles formed from acompatibilized polymeric composition of the type described hereinexhibits a heat distortion temperature of greater than 70° C., or in arange from 70° C. to 125° C., as determined in accordance with ASTMD648.

Typically the addition of PLA to a PP will increase the stiffness andconcomitantly decrease the impact strength of an injection moldedarticle, as compared to the stiffness and impact strengths of aninjection molded article formed from the PP. In contrast, the end-useinjection molded articles formed from the compatibilized polymericblends of the present invention may advantageously provide both improvedstiffness (i.e., tensile modulus and flexural modulus) and impactstrength (i.e., notched Izod impact strength) properties to theinjection molded article, as compared to injection molded articlesformed from conventional compatibilized PP/PLA blends. This improvedbalance in stiffness and impact properties of articles formed from thecompatibilized polymeric compositions described herein advantageouslypermit a wider range of utility of these compositions in the fabricationof injection molded articles requiring both stiffness and impactstrength.

In an embodiment, an injection molded article formed from acompatibilized polymeric composition of the type described herein is anautomotive part. The automotive part may be an interior or exterior partor structure of an automobile. Utilization of the compatibilizedpolymeric compositions described herein to form injection moldedautomotive parts advantageously provides automobile manufacturers withparts that be used to substitute parts traditionally made from metal,thereby permitting the fabrication of lighter more fuel efficient (i.e.,eco-friendly) automobiles.

EXAMPLES

The following example is given as particular embodiments of thedisclosure and to demonstrate the practice and advantages thereof. It isunderstood that the example is given by way of illustration and is notintended to limit the specification or the claims to follow in anymanner.

Example 1

The first example demonstrates the effect of various reactive modifierson the mechanical properties of polymeric blends comprisingpolypropylene heterophasic copolymer (PPHC) as the base polymer, PLA anda reactive modifier. For comparison purposes, the first sample(Sample 1) is a polypropylene heterophasic copolymer (“PPHC”)commercially available as neat Total Petrochemicals 4820WZ (“4820WZ”)having 9 wt. % ethylene based on the total weight of the PPHC, referredto herein as the PPHC reference sample. Also for comparison purposes,the second sample (Sample 2) is a blend of PPHC 4820WZ and a polylacticacid polymer commercially available as NatureWorks® PLA Polymer 3251D(“3251D”), referred to herein as PPHC/PLA blend, wherein the PPHC ispresent in a concentration of about 95 wt. % and the PLA has aconcentration of about 5 wt. % based on the total weight of the blend.The remaining samples (i.e., Sample 3 through Sample 8) consist of ablend of 93 wt. % PPHC 4820WZ. 5 wt. % PLA 3251, and 2 wt. % of areactive modifier. The reactive modifier incorporated into the thirdsample (Sample 3) blend is PP-g-Nylon 6, which was fabricated but isalso commercially widely available. The reactive modifier incorporatedinto the fourth sample (Sample 4) blend is highly grafted PP-g-GMA(“HGGMA”) produced as previously described in the above disclosure. Thereactive modifier incorporated into the fifth sample (Sample 5) blend isLotader® AX8840, which is a random copolymer of PE-co-GMA which iscommercially available from Arkema. The reactive modifier incorporatedinto the sixth sample (Sample 6) blend is Polybond® 3150, which is amaleic anhydride grafted propylene containing about 0.5 wt. % maleicanhydride commercially available from Chemtura. The reactive modifierincorporated into the seventh sample (Sample 7) blend is EMAC® PlusSP1307, which is a 20% ethylene-methyl acrylate (EMA) block copolymercommercially available from Westlake Chemical Corporation. The reactivemodifier incorporated into the eighth sample (Sample 8) blend is Kraton®G1643 M, which is a linear triblock copolymer based on styrene andethylene/butylenes (SEBS) having a styrene content of 20% andcommercially available from Kraton Performance Polymers, Inc. Theformulations of each of the samples (Samples 1-8) were melt blendedusing a Leistritz 27 mm twin-screw extruder. The eight samples wereextruded, pelletized, and then injection molded into standard barspecimens and ⅛ inch plaques for mechanical testing. The formulations,MFR, and mechanical properties of Samples 1-8 are summarized in Table 1.

TABLE 1 Sample 1 Sample 2 Sample 3 Sample 4 Blend PPHC 4820WZ 4820WZ4820WZ 4820WZ wt. % PPHC 100 wt. % 95 wt. % 93 wt. % 93 wt. % 5 wt. %PLA — 3251D 3251D 3251D 2 wt. % modifier — — PP-g- HGGMA Nylon 6Properties MFR [dg/min.] 33.9 39.7 34.6 35.5 Flexural modulus [kpsi] 197230 229 231 Tensile modulus [kpsi] 212 233 235 233 Tensile yieldstrength [psi] 3682 3715 3772 3785 Tensile elongation at yield [%] 3.83.1 3.1 3.0 Tensile strength at break [psi] 2488 2675 2924 2780 Tensileelongation at break [%] 30 23 19 22 Izod Impact-Notched [ft-lb/in] 1.021.2 1.11 1.12 Sample 5 Sample 6 Sample 7 Sample 8 Blend PPHC 4820WZ4820WZ 4820WZ 4820WZ wt. % PPHC 93 wt. % 93 wt. % 93 wt. % 93 wt. % 5wt. % PLA 3251D 3251D 3251D 3251D 2 wt. % modifier Lotader Polybond EMACKraton AX8840 3150 SP1307 G1643M Properties MFR [dg/min.] 34.3 36 32.635.3 Flexural modulus [kpsi] 200 210 209 180 Tensile modulus [kpsi] 219235 224 188 Tensile yield strength [psi] 3580 3827 3563 3355 Tensileelongation at yield [%] 3.1 3.1 3.1 4.1 Tensile strength at break [psi]2567 2792 2728 2295 Tensile elongation at break [%] 29 23 23 32 IzodImpact-Notched [ft-lb/in] 1.33 1.21 1.24 1.61

The data in Table 1 shows that only a small amount of PLA (i.e., 5 wt.%) in the blend of Sample 2 can significantly increase the stiffness ofthe PPHC polymer (Sample 1) as reflected in about a 17% increase inflexural modulus (i.e., from 197 kpsi to 230 kpsi) and about a 10%increase in tensile modulus (i.e., from 212 kpsi to 233 kpsi). Sample 3through 8 demonstrate that the addition of 2% various reactive modifierscan be utilized to further tweak or vary the stiffness and impact valuesof the PPHC/PLA blends, depending upon the stiffness and impact valuesrequired for the particular application of an injection molded article.FIG. 1 is a plot of impact strengths as a function of flexural modulusfor each of samples. For injection molding article applications thatrequire both high impact and high flexural modulus, a comparison ofSamples 3 through 8, as compared to reference Samples 1 and 2,demonstrates that the blends of Sample 3 (formulated using PP-g-Nylon 6as the reactive modifier) and Sample 4 (formulated using HGGMA as thereactive modifier) have the best overall balance of mechanicalproperties (e.g., flexural modulus, tensile modulus, and notched Izodimpact strength). However, it is noted that the reactive modifier inSample 3 causes a some discoloration of the polymer in terms of anincrease in yellowing where Y1 is equal to 18.55 (as determined by ASTMD1925) and in Color b where Color b is equal to 8.33, whereas Sample 4exhibits a Y1 equal to 4.96 and Color b equal to 2.7.

Example 2

In an effort to achieve superior stiffness/impact balance of PP/PLAblends, the second example demonstrates the effect of higher ethylenecontent polypropylene heterophasic copolymer as the base polymer andhigher concentrations of both PLA and reactive modifier (as compared tothe samples prepared in the previous first example) on the mechanicaland thermophysical properties of polymeric blends comprising PPHC, PLAand a reactive modifier. For comparison purposes, the ninth sample(Sample 9) is a polypropylene heterophasic copolymer (“PPHC”)commercially available as Total Petrochemicals 5571 (“5571”) having 11wt. % ethylene based on the total weight of the PPHC, referred to hereinas the PPHC reference sample. Also for comparison purposes, the tenthsample (Sample 10) is a blend of PPHC 5571 and a polylactic acid polymercommercially available as NatureWorks® PLA Polymer 6202D (“6202D”),referred to herein as the PPHC/PLA blend, wherein the concentrations ofPPHC and PLA are about 90 wt. % and 10 wt. %, respectively, based on thetotal weight of the blend. The eleventh sample (Sample 11) is a blend of85 wt. % PPHC 5571. 10 wt. % PLA 6202D, and 5 wt. % highly graftedPP-g-GMA (“HGGMA”) as the reactive modifier. The HGGMA reactive modifierwas produced as previously described in the above disclosure. Thetwelfth sample (Sample 12) is a blend of 85 wt. % PPHC 5571, 10 wt. %PLA 6202D, and 5 wt. % Lotader® AX8840 as the reactive modifier. Aspreviously mentioned, Lotader® AX8840 which is a random copolymer ofPE-co-GMA commercially available from Arkema. The formulations of eachof the samples (Samples 9-12) were melt blended using a Leistritz 27 mmtwin-screw extruder. The four samples were extruded, pelletized, andthen injection molded into standard bar specimens and ⅛ inch plaques formechanical testing. The formulations, MFR, and mechanical properties ofSamples 9-12 are summarized in Table 2.

TABLE 2 Sample 9 Sample 10 Sample 11 Sample 12 Blend PPHC 5571 5571 55715571 wt. % PPHC 100 wt. % 90 wt. % 85 wt. % 85 wt. % 10 wt. % PLA —6202D 6202D 6202D  5 wt. % modifier — — HGGMA Lotader AX8840 PropertiesMFR [dg/min.] 7.0 10.0 10.8 7.0 Flexural modulus [kpsi] 182 ± 4 215 ± 7 220 ± 4 212 ± 4 Tensile modulus [kpsi]   183 ± 1.5  217 ± 1.0   223 ±0.6   207 ± 1.8 Tensile yield strength [psi] 3446 ± 27 3674 ± 6  3789 ±11 3551 ± 21 Tensile elongation at yield [%] 5.0 3.3 3.4 3.5 Tensilestrength at break [psi] 2353 ± 125 2071 ± 126 2212 ± 65  1801 ± 328Tensile elongation at break [%]   63 ± 3.1   27 ± 4.6   27 ± 2.0   29 ±4.5 Izod Impact-Notched [ft-lb/in] 2.05 1.62 1.52 1.96 HDT [° C.] 86.191.1 92.8 83.3

The data in Table 2 shows that 10 wt. % PLA in the blend of Sample 10significantly increases the stiffness of the PPHC polymer (Sample 9) byapproximately 18%, as reflected in the increases in both the flexuralmodulus (i.e., from 182 kpsi to 215 kpsi) and tensile modulus (i.e.,from 183 kpsi to 217 kpsi), and increases the tensile yield strength bynearly 7% and the heat distortion temperature (HDT) by 5° C. The blendof Sample 11 shows that the incorporation of HGGMA as the reactivemodifier can further increase these properties (i.e., flexural modulus,tensile modulus, tensile yield strength, and HDT), which indicates thatthe efficiency of using PLA to modify polypropylene was further improvedupon compatibilization. In contrast, the blend of Sample 12 exhibits adecrease in these properties (i.e., flexural modulus, tensile modulus,tensile yield strength, and HDT) which indicates that the reactivemodifier Lotader® AX8840 did not perform as effectively as the reactivemodifier (HGGMA) in Sample 11 in terms of increasing material stiffness.With respect to impact strength, using PPHC 5571 with higher ethylenecontent of 11 wt. % increases the impact strength, as compared to theimpact strength of the PPHC 4820WZ utilized in the previous firstexample having an ethylene content of 9 wt. %. However, as expected, theincorporation of PLA into Samples 10, 11, and 12 moderately lowered theimpact strength of the PPHC (Sample 9). In conclusion, the PPHC/PLAblend compatibilized with HGGMA (i.e., Sample 11) resulted in morebalanced mechanical and thermophysical properties.

Example 3

In an effort to further increase the impact strength of PP/PLA blendswithout sacrificing stiffness, the third example demonstrates the effectof higher ethylene content polypropylene heterophasic copolymer as thebase polymer (as compared to the samples prepared in the previous firstand second examples) and several different concentrations of PLA andreactive modifier on the mechanical and thermophysical properties ofpolymeric blends comprising PPHC, PLA, and highly grafted PP-g-GMA(“HGGMA”) as the reactive modifier. For comparison purposes, thethirteenth sample (Sample 13) is a polypropylene heterophasic copolymer(“PPHC”) commercially available as Total Petrochemicals 7810 (“7810”)having 13.5 wt. % ethylene based on the total weight of the PPHC,referred to herein as the PPHC reference sample. Also for comparisonpurposes, the fourteenth sample (Sample 14) is a blend of PPHC 7810 anda polylactic acid polymer commercially available as NatureWorks® PLAPolymer 6202D (“6202D”), referred to herein as the PPHC/PLA blend,wherein the concentrations of PPHC and PLA are about 90 wt. % and 10 wt.%, respectively, based on the total weight of the blend. The fifteenthsample (Sample 15) is a blend of 85 wt. % PPHC 7810, 10 wt. % PLA 6202D,and 5 wt. % HGGMA as the reactive modifier. The HGGMA reactive modifierwas produced as previously described in the above disclosure. Thesixteenth sample (Sample 16) is a blend of 92 wt. % PPHC 7810, 5 wt. %PLA 6202D, and 3 wt. % HGGMA. The seventeenth sample (Sample 17) is ablend of 75 wt. % PPHC 7810, 20 wt. % PLA 6202D, and 5 wt. % HGGMA. Alsofor comparison purposes, the eighteenth sample (Sample 18) comprisesanother polypropylene heterophasic copolymer commercially available asTotal Petrochemicals 9760 (“9760”) haying 8 wt. % ethylene based on thetotal weight of the PPHC. Sample 18 is a blend of 85 wt. % PPHC 9760, 10wt. % PLA 6202D, and 5 wt. % HGGMA. The formulations of each of thesamples (Samples 13-18) were melt blended using a Leistritz 27 mmtwin-screw extruder. The six samples were extruded, pelletized, and theninjection molded into standard bar specimens and ⅛ inch plaques formechanical testing. The formulations, MFR, and mechanical properties ofSamples 13-18 are summarized in Table 3.

TABLE 3 Sample Sample Sample Sample Sample Sample 13 14 15 16 17 18Blend PPHC 7810 100 wt. % 90 wt. % 85 wt. % 92 wt. %  75 wt. % — PPHC9760 — — — — — 85 wt. % PLA 6202D — 10 wt. % 10 wt. % 5 wt. % 20 wt. %10 wt. % HGGMA — —  5 wt. % 3 wt. %  5 wt. %  5 wt. % Properties MFR[dg/min.] 13.4  12.8  12.2  12.1  15.2    26.3 Density [g/cm³]   0.8956  0.9215   0.9251   0.9086   0.9513 09291  Flexural modulus 148 ± 1 182± 1 187 ± 5 170 ± 4 214 ± 2 258 ± 3 [kpsi] Tensile tests Modulus [kpsi]161 ± 1 183 ± 2 192 ± 2 176 ± 2 213 ± 1 248 ± 1 Yield strength 2882 ± 123045 ± 31 3171 ± 29 2952 ± 34 3594 ± 23 4032 ± 35 [psi] Elongation at4.6 3.4 3.3 3.8 2.9    2.9 yield [%] Strength at break 2415    1992   2232    2363    2323     2606 [psi] Elongation at 250 ± 5  29 ± 3  34 ±4 180 ± 9  14 ± 1  14 ± 1 break [%] Izod Impact- 11.82  8.99  3.39 12.15 1.31    0.79 Notched [ft-lb/in] HDT [° C.] 86.1  73.3  78.3  82.8 70.6    96.7

The data in Table 3 shows that shows 10 wt. % PLA in the blend of Sample14 significantly increases the stiffness of the PPHC polymer (Sample 13)as reflected in about a 23% increase in flexural modulus (i.e., from 148kpsi to 182 kpsi) and about a 14% increase in tensile modulus (i.e.,from 161 kpsi to 183 kpsi). The blend of Sample 15 shows that theincorporation of HGGMA as the reactive modifier can further increasestiffness (i.e., flexural modulus and tensile modulus), which indicatesthat the efficiency of using PLA to modify polypropylene was furtherimproved upon compatibilization. The blend of Sample 15 also showshigher tensile strengths (i.e., tensile yield strength and tensile breakstrength) and slightly higher tensile elongation at break, as comparedto Sample 14, which indicates that the use of HGGMA as the reactivemodifier increases the material toughness. Even though the PLA dispersedbetter upon compatibilization in Sample 15, the impact strength of thematerial decreased to 3.39 ft-lb/in. However, it is notable that thenotched Izod impact resistance of Sample 15 was still greater than 3ft-lb/in. As expected, Sample 16 shows that a decrease in PLAconcentration 5 wt. % PLA) decreases the material stiffness. Conversely.Sample 17 shows that an increase in PLA concentration (i.e., 20 wt. %PLA) increases stiffness. It is notable that the blend of Sample 16exhibited an increase in impact strength, as compared to Sample 14, andis comparable to the notched Izod impact strength of the referenceSample 13. A comparison of Sample 15 and Sample 18 demonstrates that theuse of a lower ethylene content (8 wt. %) polypropylene heterophasiccopolymer (PPHC 9760) can substantially increase a material's stiffnessand concomitantly decrease its impact strength. In conclusion, thePPHC/PLA blend compatibilized with HGGMA (i.e., Sample 11) resulted inmore balanced stiffness and impact properties which may be required incertain applications, such as injection molding of automotive parts, forexample. Compatibilized polymeric blends (comprising biodegradable PLA)that exhibit a better balance in stiffness and impact properties may beadvantageously utilized as bio-sourced materials that provide a moreeco-friendly alternative to metal in the fabrication of automotiveparts.

With respect to heat distortion temperature (HDT), the addition of PLAdid not increase the HDT, as was observed in Samples 9 and 10 in theprevious second example. It is believed that this result is probably dueto PLA not fully crystallizing in the base polymer PPHC 7810 due tocertain variations in processing conditions. However, the use of HGGMAas a reactive modifier in Samples 15 and 16 did increase the HDT of PPHC7810 (as was also observed in Sample 11 as compared to Sample 10 in theprevious second example). The lower HDT value of Sample 17 may be theresult of too small a concentration of HGGMA relative to the highconcentration of PLA in the feedstock of this blend. Thus, the HGGMAreactive modifier increases the HDT of PPHC/PLA blends, as compared tonon-compatibilized PPHC/PLA blends, which improves the thermophysicalproperties of polymeric blends comprising PPHC, PLA, and highly graftedPP-g-GMA (“HGGMA”) as the reactive modifier.

Example 4

The fourth example demonstrates the effect of adding PLA and highlygrafted PP-g-GMA (“HGGMA”) as the reactive modifier on the mechanicalproperties of commercially available polymeric blends comprising PPHCand inorganic filler (i.e., talc). The nineteenth sample (Sample 19) isa non-biodegradable polymeric blend as EBP-830 from Total Petrochemicals(Feluy) that may be utilized for constructing interior automotive parts.EBP-830 is a polymer blend of 60 wt. % polypropylene heterophasiccopolymer PPHC 9760 (ethylene content of 8 wt. %), 10 wt. % ethylenepropylene diene monomer (EPDM), and 30 wt. % talc as the inorganicfiller. The incorporation of EPDM into the blend may provide additionalimpact resistance to the blend and, in effect, compensate for the lowrubber content (8 wt. % C₂) of PPHC 9760. The twentieth sample (Sample20) is a blend of 85 wt. % EBP-830, 10 wt. % polylactic acid polymer PLA6202D, and 5 wt %. HGGMA which provides a compatibilzed blend of 51 wt.% PPHC 9760, 8.5 wt. % EPDM, 25.5 wt. % talc, 10 wt. % PLA 6202D. and 5wt % HGGMA. The twenty-first sample (Sample 21) is a non-biodegradablepolymer blend as SR-64 from Total Petrochemicals which is a polymerblend of 30 wt. % polypropylene heterophasic copolymer PPHC 9760, 38 wt.% polypropylene heterophasic copolymer PPHC 7810 (ethylene content of13.5 wt. %), 10 wt. % high density polyethylene (HDPE) which iscommercially available as product M6091 (“M6091”) from TotalPetrochemicals, 15% talc steamic OOS which is commercially available atLuzenac, and 7% Tafmer A1050S which is commercially available at Mitsui.The incorporation of HDPE into the blend may provide some additionalimpact resistance and scratch resistance of the polymeric blend whilemaintaining the stiffness of the blend. The twenty-second sample (Sample22) adds PLA 6202D and HGGMA to the composition of Sample 21, to providea compatibilized blend of 25.5 wt. % PPHC 9760, 32.3 wt. % PPHC 7810,5.95 wt. % HDPE M6091, 5.95% EPDM, and 12.75 wt. % talc. 10 wt. % PLA6202D, and 5 wt % HGGMA. The formulations of each of the samples(Samples 19-22) were melt blended using a Leistritz 27 mm twin-screwextruder. The four samples were extruded, pelletized, and then injectionmolded into standard bar specimens and ⅛ inch plaques for mechanicaltesting. The formulations, MFR, and mechanical properties of Samples19-22 are summarized in Table 4.

TABLE 4 Sample 19 Sample 20 Sample 21 Sample 22 Blend PPHC 9760 (8 wt. %C2) 60 wt. % 51 wt. % 30 wt. % 25.5 wt. % PPHC 7810 (13.5 wt. % C2) — —38 wt. % 32.3 wt. % EPDM 10 wt. % 8.5 wt. %   7 wt % 5.95 wt % HDPEM6091 — — 10 wt. % 8.50 wt. % talc 30 wt. % 25.5 wt. %   15 wt. % 12.75wt. %  PLA 6202D — 10 wt. % —   10 wt. % HGGMA —  5 wt. % —   5 wt. %Properties MFR [dg/min.] 11.6 10.0 7.4 9.2 Density [g/cm³] 1.0929 1.11450.9827 1.0163 Flexural modulus [kpsi] 459 491 203 240 Tensile testsModulus [kpsi] 293 367 205 247 Yield strength [psi] 3404 3902 3025 3391Elongation at yield [%] 2.2 1.7 5.0 3.1 Strength at break [psi] 23033228 2076 2415 Elongation at break [%] 21 8 60 25 Izod Impact-Notched[ft-lb/in] 2.73 0.71 10.7 1.82 HDT [° C.] 124 119 92 84

The data in Table 4 shows that compatibilization of PLA with highlygrafted PP-g-GMA in the blend of Sample 20 increases the stiffness andtensile mechanical properties of the Sample 19 blend as reflected by a7% increase in flexural modulus, a 25% increase in tensile modulus, a15% increase in tensile yield strength, and a 40% increase in thetensile break strength. While the increases in tensile mechanicalproperties are substantial, there is also a decrease in the notched Izodimpact strength and HDT temperature. Similar results were obtained inSample 22. In particular, compatibilization of PLA with highly graftedPP-g-GMA in the blend of Sample 22 increases the stiffness and tensilemechanical properties of the Sample 21 blend as reflected by an 18%increase in flexural modulus, a 21% increase in tensile modulus, a 12%increase in tensile yield strength, and a 16% increase in the tensilebreak strength. Thus, the flexural and tensile mechanical properties ofthe EBP-830 and SR-64 formulations comprising inorganic filler may befurther enhanced by the incorporation of PLA and HGGMA.

Example 5

The fifth example demonstrates the effect of adding PLA and highlygrafted PP-g-GMA (“HGGMA”) as the reactive modifier on the hightemperature mechanical properties of heterophasic propylene copolymers.For comparison purposes, the twenty-third sample (Sample 23) is apolypropylene heterophasic copolymer (“PPHC”) commercially available asTotal Petrochemicals 5571 (“5571”) having 11 wt. % ethylene based on thetotal weight of the PPHC. Also for comparison purposes, thetwenty-fourth sample (Sample 24) is a blend of PPHC 5571 and apolylactic acid polymer commercially available as Nature Works® PLAPolymer 6202D (“6202D”), referred to herein as the PPHC/PLA blend,wherein the concentrations of PPHC and PLA are about 90 wt. % and 10 wt.%, respectively, based on the total weight of the blend. Thetwenty-filth sample (Sample 25) is a blend of 85 wt. % PPHC 5571, 10 wt.% PLA 6202D, and 5 wt. % highly grafted PP-g-GMA (“HGGMA”) as thereactive modifier. The HGGMA reactive modifier was produced aspreviously described in the above disclosure. The twenty-sixth sample(Sample 26) is a blend of 75 wt. % PPHC 5571, 20 wt. % PLA 6202D, and 5wt. % highly grafted PP-g-GMA (“HGGMA”) as the reactive modifier. Thefour samples were extruded, pelletized, and then injection molded intostandard bar specimens for mechanical testing. The mechanical propertiesof Samples 23-26 at 23° C., 50° C. and 80° C. are summarized in FIGS. 2and 3.

The data in FIGS. 2 and 3 show that, as expected, materials Young'smodulus and tensile yield strengths decrease as the testing temperatureincreases. Addition of 10 wt. % PLA in the blend of Sample 24significantly increases the stiffness and tensile strengths of the PPHCpolymer (Sample 23), whichever test temperature is used. The blend ofSample 25 shows that the incorporation of HGGMA as the reactive modifiercan further increase the Young's modulus and strength, even though aslightly lower stiffness is obtained at 80° C. Addition of 20% PLA inthe blend of Sample 26 can further improve mechanical properties atdifferent temperatures. Overall, presence of PLA does not have anynoticeable detrimental effect on material tensile mechanical propertieseven at high temperatures.

Example 6

The sixth example demonstrates the effect of thermal aging on themechanical properties of heterophasic propylene copolymer-basedmaterials. The four samples in the Example 5 were extruded, pelletized,and then injection molded into standard bar specimens. The specimenswere then aged at 100° C. and 150° C. for a number of days. Then thespecimens were taken out of the aging oven and tested for tensilemechanical properties at room temperature. The mechanical properties ofthe specimens aged at 100° C. are summarized in FIGS. 4 and 5, and apicture of the specimens aged at 150° C. for 30 days are summarized inFIG. 6.

The data in FIG. 4 show that the Samples #24 through 26 containing PLAwith or without reactive modifier possess higher stiffness than Sample#23 neat PPHC 5571 upon thermal aging at 100° C. for different times.Specifically, under each aging condition, presence of PLA in Sample 24significantly increases stiffness of the heterophasic copolymer Sample23. The blend of Sample 25 shows that the incorporation of HGGMA as thereactive modifier can further increase the stiffness, which indicatesthat the efficiency of using PLA to modify polypropylene was furtherimproved upon compatibilization. The blend of Sample 25 shows thataddition of more PLA 20 wt % can further significantly increase thestiffness, even though the stiffness drops when the sample was aged at100° C. for about 30 days.

The data in FIG. 5 show that the effect of thermal aging on tensileyield strengths of the samples is different from sample to sample. Incomparison with neat PPHC 5571 Sample 24, simple blend of PPHC 5571 andPLA shows lower tensile strengths upon thermal aging. However, whencompatibilizer HGGMA is used, the materials become more stable,exhibiting increased tensile strength upon thermal aging, retainingsuperior yield strengths over neat PPHC 5571 Sample 23 under all theaging conditions. FIG. 6 shows the pictures of the Samples 23 through 26after being aged at 150° C. for one month. Simple PPHC 5571 blend withPLA Sample 24 become brown color and very weak with no strength at all.However, with same amount of PLA content, the compatibilized Sample 25still possesses its integrity and strength under the same conditions.Without being limited by any theory, it is speculated that use of HGGMAreactive modifier could consume the acid groups of PLA molecules and mayalso extend PLA molecular chains, making the PLA more thermally stable.Overall, in general presence of PLA does not have significantlydetrimental effect on material tensile mechanical properties uponthermal aging. Compatibilization could significantly improve thermalstability of polyolefin-PLA blend materials.

While the foregoing is directed to embodiments of the present invention,other and further embodiments of the invention may be devised withoutdeparting from the basic scope thereof and the scope thereof isdetermined by the claims that follow.

What is claimed is:
 1. A method of forming an injection molded articlecomprising: providing a polyolefin comprising one or more propyleneheterophasic copolymers, the polyolefin having an ethylene content of atleast 10 wt. % based on the total weight of the polyolefin; meltblending the polyolefin with a polylactic acid and a reactive modifierto form a compatiblized polymeric blend, wherein the reactive modifiercomprises a glycidyl methacrylate grafted polypropylene (PP-g-GMA) thatis produced by contacting a polypropylene, a glycidyl methacrylate., amultifunctional acrylate comonomer, and an initiator under conditionssuitable for the formation of the PP-g-GMA having a grafting yield in arange from 1 wt. % to 15 wt. %; and injection molding the compatibilizedpolymeric blend into an article.
 2. The method of claim 1, wherein theone or more propylene heterophasic copolymers has an average ethylenecontent in a range from 11.5 wt. % to 18 wt. % based on the total weightof the copolymers.
 3. The method of claim 1, wherein the polyolefinfurther comprises an elastomer comprising ethylene.
 4. The method ofclaim 1, wherein the polyolefin further comprises polyethylene.
 5. Themethod of claim 1, wherein the polyolefin has an ethylene content in arange from 11.5 wt. % to 18 wt. % based on the total weight of thepolyolefin.
 6. The method of claim 1, wherein the melt blending stepincludes melt blending the polyolefin with the polylactic acid, aninorganic filler, and the reactive modifier to form the compatiblizedpolymeric blend.
 7. The method of claim 1, wherein the polylactic acidhas a concentration of from about 3 wt. % to about 20 wt. % based on theweight of the compatibilized polymeric blend.
 8. The method of claim 1,wherein the reactive modifier has a concentration in a range from about1 wt. % to about 15 wt. % based on the weight of the compatibilizedpolymeric blend.
 9. The method of claim 1, wherein the multifunctionalacrylate comonomer is selected from polyethylene glycol diacrylate,alkoxylated hexanediol diacrylate, trimethylolpropane triacrylate,propoxylated neopentyl glycol diacrylate, ethoxylated trimethylolpropanetriacrylate, diethylene glycol diacrylate,tris(2-hydroxyethyl)isocyanurate triacrylate, and combinations thereof.10. The method of claim 1, wherein the grafting yield of glycidylmethacrylate (GMA) is from 1.5 wt. % to 10 wt. %.
 11. The method ofclaim 1, wherein the grafting yield of glycidyl methacrylate (GMA) is ina range from about 2 wt. % to about 15 wt. %.
 12. The method of claim 1,wherein the multifunctional acrylate comonomer is selected frompolyethylene glycol diacrylate, alkoxylated hexanediol diacrylate,propoxylated neopentyl glycol diacrylate, diethylene glycol diacrylate,tris(2-hydroxyethyl)isocyanurate triacrylate, and combinations thereof.13. The method of claim 1, wherein the PP-g-GMA that is produced bycontacting from 80 wt.% to 99.5 wt.% of the polypropylene, from 0.5 wt.%to 20 wt.% of the glycidyl methacrylate, from 0.5 wt.% to 15 wt.% of themultifunctional acrylate comonomer, and from 0.05 wt. % to 1.5 wt.% ofthe initiator under conditions suitable for the formation of thePP-g-GMA.
 14. The method of claim 1, wherein the article exhibits aflexural modulus in a range from 150 kpsi to 500 kpsi.
 15. The method ofclaim 1, wherein the article exhibits a tensile modulus in a range from170 kpsi to 400 kpsi.
 16. The method of claim 1, wherein the articleexhibits a tensile yield strength in a range from 2800 psi to 4500 psi.17. The method of claim 1, wherein the article exhibits a notched Izodimpact strength in a range from 2.1 ft-lb/in to 15 ft-lb/in.
 18. Themethod of claim 1, wherein the article exhibits a flexural modulus of atleast 150 kpsi and a notched Izod impact strength in a range from 2.1ft-lb/in to 15 ft-lb/in.
 19. The method of claim 1,wherein the articleexhibits a flexural modulus of at least 150 kpsi and a notched Izodimpact strength in a range from 3 ft-lb/in to 15 ft-lb/in.
 20. Themethod of claim 1, wherein the article is an automotive part.